Hello,
There are many models under the HP DV7 series, if you could you provide me with the HP product or the exact model number then maybe I can be of help to you.
You can find the HP product number beneath the laptop or inside the battery compartment. It should something similar to this one - RQ236AA#ABA. If you are not able to find it then try this link -
Guide to finding HP product number. <- Click here.
Yes, it is possible to upgrade unless you had already configured the laptop to the max at the time of purchase. When I think of speed there are two rather three H/w components that can be upgraded namely, memory(RAM), HDD to an SSD and the CPU. But the most easiest and the effective upgrade is memory. I do not know if you can upgrade the processor for your laptop (anyway I think that will void the warranty) but there's a probability for the SSD upgrade but not sure as I haven't tried it yet.
But anyway do let me know the HP product number (p/n), I will find you some upgrades for your laptop. Cheers